1. Field of the Invention
The present invention relates to an image processing method which optically reads an image recorded onto a photographic film which has been developed by dry development and determines an image processing parameter for generating a digital image data.
2. Description of the Related Art
Conventionally, graininess in a photographic print is primarily caused by exposure at the time of photographing and is influenced by underexposure or overexposure of the photographic print. The greater the underexposure at the time of photographing, the more conspicuous the graininess.
The graininess is secondarily caused by enlargement ratio at the time of printing. The larger the enlargement ratio at the time of printing, the more conspicuous the graininess.
Further, the graininess is thirdly caused by ISO sensitivity. In a current photographic film, the higher the ISO sensitivity, the more grainy and more conspicuous the graininess.
It is preferable that the above-described image processing parameter be determined in accordance with the respective contribution ratios of the causes.
Sharpness emphasizing degree, reproduction of contrast in an image of an underexposed photographic film, or the like as an image processing parameter has a trade-off relationship to granularity. Accordingly, it is particularly important to set an optimal image processing parameter. Among the above causes, the first cause, i.e., exposure at the time of photographing, can be determined by the density of the photographic film. The second cause, i.e., enlargement ratio of a print, is carried out by the designation of an operator and can be naturally recognized by a photographic processing apparatus.
On the contrary, in the third cause, i.e., ISO sensitivity, a new sensor which reads a DX code recorded on a photographic film must be provided. Accordingly, the number of parts for the apparatus is increased and the device becomes large and complicated.
Silver image remains in particular in a photographic film which is processed by dry development, and the graininess of the silver image is added thereto. Consequently, unless the optimal image processing parameter is set, the degree of influence due to the graininess of the silver image increases. Further, in order to reproduce color saturation, the graininess of the photographic film subjected to dry development deteriorates more than that of a photographic film subjected to wet development.